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Geography Lecture 1-7.docx

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Reg Horne

Geography: Goal: -current environmental issues -using systems approach: stresses interrelationships between physical environment and societies -see the big picture and connect the dots -systems in the Earth: role and function Lecture One: Systems: function together as a whole even through its made of many different parts; no difference between human and physical systems *Change is the only true fact in the universe* Types of systems: Open systems: exchange a lot of energy and matter with outside systems (ex. A human body) Closed systems: exchange energy but not matter with outside systems (ex. The Earth) Isolated systems: doesn’t exchange energy or matter with outside systems (ex. A closed thermos bottle) Properties of a system: Components: -systems made up of diverse components that function as a whole -there is a flow of energy and mass between the components Equilibrium State: -system will not change unless there is a disturbance Stable equilibrium: system will return to this state if slightly disturbed Unstable equilibrium: a small disturbance will carry a system from one equilibrium state to another Threshold event: small change that causes the systems to shift from one equilibrium state to another Disturbances: Perturbation: temporary disturbance (ex. Mt. Pinatubo eruption: climate cooled , then returned to normal Forcing: A more persistent disturbance (ex. Global warming) Feedback loops: -a type of interaction between components of a system (ex. A change in component one causes a change in component two, which in turn comes back to effect component one) Earth as a closed system: Four spheres within the closed system- Within a closed system there are four major inter-connected components: -geosphere -hydrosphere -atmosphere -biosphere Energy and matter are exchanged between these components Lecture 2: Geosphere, Hydrosphere, Atmosphere and Biosphere: Why can the Earth sustain life? -it isn’t to close or too far from the sun -it is large enough to hold an atmosphere -there is an abundance of water -the temperature ranges to allow water in liquid, gaseous and solid forms The geosphere: -solid, inorganic Earth, including Earth’s surface and layers of its interior -the Earth is composed of shells that are classified according to chemical and mechanical function Important Roles: 1. Contributes matter to the atmosphere 2. Contributes salt to the ocean (ions being released from the weathering rock) 3. Source of nutrients for living things on earth 4. Contributor to atmospheric gases (from volcanoes) 5. Movement of plants produces barriers that aid in the isolation of population of organisms The Dynamic Geosphere: -things that occur beneath the Earth’s surface manifest in earthquakes and volcanoes -this is linked to the movement of the tectonic plates The hydrosphere: -is composed of all the water in the Earth’s system -including all the water on top and inside the Earth -97% of the Earth’s water is in the oceans, the remaining 3% is fresh water (in ice sheets, in the air and under the Earth’s surface) *presence of liquid surface water makes our planet unique* Important Roles: 1. Moderates climate 2. Transfers heat 3. Organisms use water to transport was and nutrients 4. Water is needed for many of the earth’s processes Lecture 3: The atmosphere: -body of gases that surround the Earth -most of atmosphere is located close to the Earth and is very -the air in the atmosphere is 79% nitrogen and just under 21% oxygen (the rest is composed of carbon dioxide and other gases) -atmosphere has many different levels Important Roles: 1. Contains gases that all living thing need to live 2. Transfers heat (through driving force of wind) 3. Ozone in the stratosphere protects living things from ultraviolet radiation 4. Plays a part in weathering and erosion The biosphere: -includes all living things (plants, animals, microbes and organic material that is not yet composed) -most of Earth’s life is found about 3 meters below ground, 30 meters above it and in the top 200 meters of the oceans and seas -life can thrive in the most unlikely of places (hot springs to ice caps) Important Roles: 1. Helps with weathering 2. An important sink for certain elements (especially carbon) 3. Mediates the formation of some minerals 4. Photosynthesis helps maintain the oxygen content of the atmosphere A recent addition to the biosphere is human activity To see how strongly interconnected the Earth’s spheres really are, we can think about what happens to substances within the systems (ex. The carbon cycle) *Note that at any time, carbon is in many spheres* A small-scale example: A forest fire Interactions between spheres: Cause and effect Geosphere: The ground could have been permeable, stopping moisture from staying in the upper part of the soil Hydrosphere: There could have been a lack of rain, making the area prone to fire Atmosphere: Possible lighting strike could have started the fire Biosphere: Dead wood, leaves and pine needles would have made it easier for the fire to start and spread Relevance to the geosphere: 1. Heat from the fire causes the rocks to crack and weather 2. Soil erosion is enhanced by vegetation removal 3. Ash from the fire alter the chemistry of the soil Relevance to the atmosphere: 1. Smoke and ash are carried by the wind to other areas 2. Increased rain due to ash particles acting as nucleation centers for rain drops 3. Pollutants (ex. CO2) are produced during the burning of vegetation and carried by wind Relevance to the hydrosphere: 1. Heat from the fire removes moisture for the air (through evaporation) 2. Increased siltation of streams due to erosion (particles deposited as sediment) Relevance to the biosphere: 1. Destruction of the habitat 2. Smoke in the air may cause breathing problems for humans and animals 3. Ash particles in the water may cause problems for fish and other aquatic species Positives: 4. Ash particles can benefit future plant communities 5. Some plant may require their shells burned before they can reproduce Global Effects: These interactions do not only apply to local scenarios but also changes on a global scale. Some examples of changes on a global scale are: -initiation of ice ages -mass extinctions -global climate change -El Nino event
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